The present invention relates to a mobile wireless communication system. The present invention also relates particularly to a diversity wireless transmitting/receiving system for transmitting data each including the same contents from a plurality of transmitting stations and performing diversity reception of the data by a receiving station.
In a mobile communication in which communications are conducted between base stations and a mobile station, a system has been adopted in which the mobile station performs diversity reception of signals each including the same contents from a plurality of the neighboring base stations. As one example of this type of diversity reception system, Japanese Patent Laid-open (Kokai) No. Hei 5-83181 discloses a system wherein an error check is made to each of a plurality of received signals identical in contents and one signal determined to be free of an error is selected.
In the aforementioned conventional system, information included in each signal non-selected as a result of the error check does not contribute to an improvement in the reliability of communications. As a result, transmitting power has been dissipated to satisfy required communication quality.
In the present invention, such a configuration that information included in all the signals to be selected can be effectively utilized, is adopted to reduce transmitting power for satisfying required communication quality. Described specifically, respective base stations respectively transmit those obtained by dividing a code word in an error correcting code, and a mobile station combines fragments of the divided code words and decodes the combined one, thereby bringing information to a high degree of reliability. The following problems arise at this time.
Upon firstly establishing the mobile communication, the existing locations of a mobile station are roughly divided into the two as follows:
(1) when the mobile station exists in a location where it can receive signals with suitable intensity from a plurality of base stations due to reasons such as the passage of the mobile station through a point located midway between the plurality of base stations.
(2) when the mobile station exists in a location where it is able to receive a signal with sufficient intensity from a given base station but unable to receive signals with suitable intensity from other base stations due to the reason that it is far distant therefrom, for example.
Thus, the mobile station is not always able to receive signals identical in contents from a plurality of base stations corresponding to the ever-stable number of base stations. Namely, the fragments of the code words are not always complete or available. Therefore, the mobile station has to be able to decode desired information even from one received signal from one arbitrary base station, i.e., one arbitrary fragment of each code word.
The present invention has been completed to solve the foregoing problems. Owing to the setting of encoding in respective base stations to injection, signals each including the same contents, which are received by a mobile station, are used for increasing the reliability of communications without depending on the number of the signals which were capable of being received by the mobile station, thereby reducing transmitting power for satisfying required communication quality. Further, a wireless apparatus according to the present invention comprises a plurality of wireless transmitting stations each provided with a transmitting antenna, a transmitter capable of transmission through a pre-specified radio channel, an encoder for performing encoding processing corresponding to the radio channel, and a data input interface for obtaining data to be transmitted from an external device; and a wireless receiving station including a receiving antenna, a receiver capable of independently receiving signals from a plurality of radio channels, a plurality of buffers for respectively storing received data therein according to the received radio channels, a selector A for reading the data from the plurality of buffers and sending the data to either one of a plurality of decoders and a data combiner according to the read buffers, the data combiner for combining data in predetermined order, a plurality of decoders for respectively executing predetermined decoding processes, a selector B for selecting decoded data in interlock with the selector A and outputting the same therefrom, and a data output interface for supplying the received and decoded data to an external device.
These and other objects and many of the attendant advantages of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.